Handbook of Information Security Management
(Publisher: CRC Press LLC)
Author(s): Hal Tipton and Micki Krause, Consulting Editors
ISBN: 0849399475
Publication Date: 01/01/98

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Value of Confidentiality, Integrity, and Availability. In recent years, a better understanding of the values of confidentiality, integrity, and availability and how to establish these values on a monetary basis with reasonable credibility has been achieved. That understanding is best reflected in the ISSA-published GIV referenced above. These values often represent the most significant “at risk” asset in IT environments. When an organization is deprived of one or more of these with regard to its business or mission information, depending on the nature of that business or mission, there is a very real chance that unacceptable loss will be incurred within a relatively short time. For example, it is well-accepted that a bank that loses access to its business information (loss of availability) for more than a few days is very likely to go bankrupt.

A brief explanation of each of these three critical values for information is presented below:

  • Confidentiality is lost or compromised when information is disclosed to parties other than those authorized to have access to the information. In the complex world of IT today, there are many ways for a person to access information without proper authorization if appropriate controls are not in place. Of course, it still remains possible to simply pick up and walk away with confidential documents carelessly left lying about or displayed on an unattended, unsecured PC.
  • Integrity is the condition that information in or produced by the IT environment accurately reflects the source or process it represents. Integrity may be compromised in many ways, from data entry errors to software errors to intentional modification. Integrity may be thoroughly compromised, for example, by simply contaminating the account numbers of a bank’s demand deposit records. Since the account numbers are a primary reference for all associated data, the information is effectively no longer available. There has been a great deal of discussion about the nature of integrity. Technically, if a single character is wrong in a file with millions of records, the file’s integrity has been compromised. Realistically, however, some expected degree of integrity must be established. In an address file, 99% accuracy (only 1 out of 100 is wrong) may be acceptable. However, in the same file, if each record of 100 characters had only 1 character wrong — in the account number — the records would meet the poorly articulated 99% accuracy standard, but be completely compromised. In other words, the loss of integrity can have consequences that range from trivial to catastrophic. Of course, in a bank with 1 million clients, 99% accuracy means at best that the records of 10,000 clients are in error. In a hospital, even one such error could lead to loss of life!
  • Availability, the condition that electronically stored information is where it needs to be, when it needs to be there, and in the form necessary, is closely related to the availability of the information processing technology. Whether because the process is unavailable, or the information itself is somehow unavailable, makes no difference to the organization dependent on the information to conduct its business or mission. The value of the information’s availability is reflected in the costs incurred over time by the organization, because the information was not available, regardless of cause. A useful tool (from the Modified Delphi method) for capturing the value of availability — and articulating uncertainty — is illustrated in the chart (Exhibit 3) below. This chart represents the cumulative cost, over time, of the best case and worst-case scenarios, with confidence factors, for the loss of availability of a specific information asset.

  Exhibit 3.

Vulnerability Analysis

This task consists of the identification of vulnerabilities that would allow threats to occur with greater frequency, greater impact, or both. For maximum utility, this task is best conducted as a series of one-on-one interviews with individual staff members responsible for implementing organizational policy through the management and administration of controls. To maximize consistency and thoroughness, and to minimize subjectivity, the vulnerability analysis should be conducted by an interviewer who guides each interviewee through a well-researched series of questions designed to ferret out all potentially significant vulnerabilities.

It should be noted that establishment and global acceptance of Generally Accepted System Security Principles, as recommended in the National Research Council report Computers at Risk (12/90), will go far in establishing a globally accepted knowledge base for this task.

Threat/Vulnerability/Asset Mapping

Without connecting — mapping — threats to vulnerabilities and vulnerabilities to assets and establishing a consistent way of measuring the consequences of their interrelationships, it becomes nearly impossible to establish the ramifications of vulnerabilities. Of course, intuition and common sense are useful, but how does one measure the risk and support good budgetary management and cost/benefit analysis when the rationale is so abstract?

For example, it is only good common sense to have logical access control, but how does one justify the expense? We are reminded of a major bank whose management, in a cost-cutting frenzy, came very close to terminating its entire logical access control program! With risk assessment, one can show the expected risk and annualized asset loss/probability coordinates that reflect the ramifications of a wide array of vulnerabilities. Let us carry the illustration further with two basic vulnerabilities (Exhibit 4).

Exhibit 4.

Applying some simple logic at this point will give the reader some insight into the relationships between vulnerabilities, threats, and potentially affected assets:

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